GANA Requests Feedback on VT Value in ASHRAE 90.1 Proposal

The Glass Association of North America of Topeka, Kan., will participate on the ASHRAE 90.1 Envelope Subcommittee call next week, and association officials are requesting guidance on some issues from industry professionals on how best to proceed. The subcommittee will consider a proposal to adopt a minimum Visible Transmittance (VT) within ANSI/ASHRAE/IES Standard 90.1-10 Energy Standard for Buildings Except Low-Rise Residential Buildings. Currently, Section 5.8.2.6 Visible Transmittance only states that "VT shall be determined in accordance with NFRC 200 and that it shall be verified and certified by the manufacturer." This proposal only affects commercial buildings and high-rise apartments four stories or taller, not low-rise residential.

The subcommittee is considering adoption of a single minimum VT value of 0.40 based on a daylighting analysis presentation provided by Pacific Northwest National Laboratory (PNNL) during its interim meeting in Atlanta.

GANA officials are asking that industry members participate in a